Currently, absorbent articles such as sanitary napkins, fabric absorbent pads and incontinence pads include materials that are non-water disintegratable, and after use they are discarded in waste boxes provided in toilet rooms, requiring recovery and further disposal. However, when used absorbent articles are inadvertently flushed into flush toilets when being discarded, they can clog the pipes of the flush toilets. Research has therefore been conducted on water disintegratable materials and absorbent articles comprising them, which can be flushed into flush toilets directly after use.
In particular, when a liquid-impermeable back sheet is to be used in an absorbent article it must be impermeable to excreted fluids such as menstrual blood and urine, and because it is difficult to exhibit both liquid impermeability during use and water disintegrating property after disposal, much research has been conducted in this regard.
For example, PTL 1 describes a leak-proof sheet for a hygienic pad, wherein a water-repellent layer is layered on one side of a water-soluble resin sheet and a water disintegratable base material is layered on the other side of the water-soluble resin sheet.
That is, the leak-proof sheet described in PTL 1 has a three-layer structure with a water disintegratable base material, a water-soluble resin sheet and a water-repellent layer, being designed so that the two layers, the water-repellent layer and the water-soluble resin sheet, hold absorbed fluids inside a hygienic pad and prevent leakage.